1. Field of the Invention
The present invention relates to a multi-plate clutch including a clutch hub having a cylindrical portion and a plurality of clutch plates splined to the outer periphery of the cylindrical portion of the clutch hub, and to a manufacturing method of the clutch hub configuring the multi-plate clutch together with the plurality of clutch plates.
2. Description of the Related Art
To date, as this kind of multi-plate clutch, an automatic transmission multi-plate clutch configured by incorporating stacked clutch plates, wherein a plurality of driven side clutch plates linked to a clutch hub side and a plurality of drive side clutch plates linked to a clutch retainer (clutch drum) side are alternately stacked, into a clutch retainer together with a piston, has been known (for example, refer to JP-A-5-180242). With this multi-plate clutch, the outer side end face of the stacked clutch plates incorporated into the clutch retainer is retained by a protruding portion wherein an outer peripheral portion of the clutch retainer is protruded in the inward direction in a position spaced by an amount equivalent to the endplate of the stacked clutch plates . Then, such a protruding portion is formed by protruding a spline groove ridge portion on the outer peripheral surface side at the outer side edge portion of the clutch retainer or in a position slightly deeper than the outer side edge portion, or by bending the outer side edge portion of the clutch retainer to the inner side.